To get into the launch options you:
1. Go to steam libary
2. Rightclick on CS GO
3. Properties
4. Set Launch Options
and write in the following you need from below.
-console
//Makes your console popup when you launch CS GO
-novid
//Stops all the videos that will be shown when you launch CS GO
-tickrate 128
//Makes your offline servers go 128tick rate instead of 64tickrate
-threads (number)
//Makes CS GO use all the threads of your CPU. DO NOT put any higher thread number than what your CPU got.
-high
//Sets CS GO.exe to high priorty in the task manager
+exec autoexec
//Launches the autoexec.cfg when the game starts up. (if you have made one)
-refresh (120/144)
//If you got a monitor that can handle more than 60 hertz you can put in the number of HZ your monitor got to use it ingame
CS:GO 